1. Field of Invention
The present invention relates generally to external interfaces communicating with a plurality of processing units and, more particularly, to controlling data communications between an external interface and a plurality of universal asynchronous receiver-transmitters (UARTs) each in operational relationship with at least one processor.
2. Copyright & Trademark Notices
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3. Related Art
Handheld communication and computing devices such as cellular phones and personal digital assistants (PDAs) continue to grow in popularity as the related systems and accessories become more affordable and easier to carry. While the reduction in size of a device makes it more convenient for use, it imposes limitations on system design, specially with respect to the size and number of subsystems and components that can be included on the printed circuit board (PCB) when manufacturing the device.
Generally, a handheld device uses an external communication interface (i.e., external interface) to connect to external devices such as a mouse, a flash burning device, or test equipment. The connection between a processor implemented on the PCB and the external interface is typically established via a universal asynchronous receiver-transmitter (UART). A UART is a system subcomponent that handles asynchronous serial communication. Generally, all computing systems include a UART to manage the serial ports, for example.
Certain mobile devices can include more than one processor and therefore more than one UART enabled chipset (chip), because each chip requires a separate mechanism to connect its processor to the external interface. For example, certain cellular phones have a chipset for handling GSM related communications and another chipset for handling Bluetooth related communications, wherein each chipset includes a microcontroller (i.e., processor) and a respective UART in operational relationship with the microcontroller. In order for each UART to communicate with an external device, an external interface is needed. Implementing an external interface for each UART is undesirable, however, because of the space saving requirements associated with the design of a miniature mobile device.
Other solutions such as adding hardware switches or control devices to manage routing of data between an external device and multiple UARTs are both expensive and impractical. Such solutions require addition of electronic hardware such as control PINs or relays that take up valuable space on the PCB. Further, implementation of such hardware solutions requires redesigning the system and related components. The cost associated with design, manufacture, and upgrade of such systems and components can be considerably high and therefore problematic.
A system and method is needed to overcome the above problems.